Bipolar resistive switching and substrate effect in GdK2Nb5O15 epitaxial thin films with tetragonal tungsten bronze type structure

Abstract

Ferroelectric compound GdK2Nb5O15 with tetragonal tungsten bronze type structure thin films were grown by pulsed laser deposition on (001)SrRuO3/SrTiO3 and (001)SrRuO3/LSCO/MgO substrates respectively, in the same experimental conditions. Structural properties were investigated using X-ray diffraction in different modes. θ–2θ diffraction shows a single crystalline SRO and GKN phases, with c-axis perpendicular to the substrate. Phi-scans show for both SRO and GKN an epitaxial cube-on-cube growth. Reciprocal space mapping (RSM) was performed on GKN to determine the in-plane lattice parameters, and showed that GKN grown on MgO is more constrained comparing to STO. Room temperature electrical properties were investigated using platinum (Pt) top electrodes. Results show that GKN thin films deposited on MgO and STO substrates are resistively switchable. It was found that the nature of the substrate affects strongly the resistance ratio: GKN on SRO/LSCO/MgO showed a large hysteresis comparing to GKN on SRO/STO. Resistance switching in GKN is attributed to the oxygen vacancies migration which can be controlled by the substrate or the frequency sweep.